How do I put my desktops into a grid layout instead of a single row?

Your pager is responsible for doing this, and communicates with Openbox to make sure they agree on it.
Any pager which complies with the EWMH specification should be able to do this. Examples are the gnome-panel pager and rox-pager.

If your pager does not comply with the spec, or you don't use a pager, you can use this small program to set the layout at startup, for example setlayout 0 2 2 0 for a 2x2 grid.

What is this dock I hear so much about?

The dock is where your dockapps go, if you don't have any, you don't need it. There is a large collection of dockapps available at dockapps.org that you can use.

Does anyone know of a taskbar that works well with openbox?

There are many programs listed here that you can use with Openbox, including taskbars and other things.

How do I make things start when I start Openbox?

If you are using a desktop environment - and therefore a session manager - you just need to save your session with the programs running. GNOME and KDE's session managers also both provide a way to run things on startup that aren't a part of the session, see their documentation for details.

If you run Openbox without a desktop environment and session manager, see the autostart guide.

Replace each of the commands in APPS with the dockapps you want to run, and they will appear in the dock in the order they are listed. Take care of having a \ at the end of each line, except for the last line.

I'm using rxvt-unicode or aterm, and transparency is leaving artifacts!

This will work in Openbox 3.4. If you are running an older version or have this problem with another wm, here's what to do:
By default these terminals use a transparency mode that only works by chance. They support a more proper one too. If you use aterm you have to give -sh 99 or -sh 101, with urxvt you have to give -tint white (ie in urxvt you can use -sh 100 and the proper mode). If this doesn't use the correct background image you have to use a background setting program that sets the correct hint, for example Hsetroot and Esetroot.

How do I get true 32-bit transparent windows?

True 32-bit transparency is made possible through the Composite extension. You need to have this extension enabled in your Xserver. Use this command in a terminal to make sure it is enabled:

xdpyinfo|grep Composite

It will list "Composite" if it is enabled.

As well, you need to run a composite manager for applications to access the Composite extension. You can use the xcompmgr with a command like this:

xcompmgr -c -t-5 -l-5 -r4.2 -o.55 &

Run it without any arguments if you don't want any extras like drop shadows.

You could put this command in your autostart file to make it run automatically at log in.

Lastly, you need an application which supports it, such as rxvt-unicode:

urxvt -depth 32 -fg white -bg rgba:0000/0000/0000/bbbb

You can use the transset program to give transparency to any window, with a command such as this:

transset 0.8 # then click on the window you want to make transparent

How do I remove the decorations from all my windows?

You can use the per-app settings to remove decorations from all your windows, or any group of them. The per-app settings are in the <applications> section of your ~/.config/openbox/rc.xml (or the system-wide /etc/xdg/openbox/rc.xml).

Here is an example that would remove decorations from all of your windows except Firefox:

There is a more complicated example showing many of the things you can do with per-app settings in the upgrading to 3.4 guide.

Where did my Debian menu go?

The short answer is: nowhere. If you previously had an official Debian Openbox .deb installed and saw the Debian Menu in the root menu, the files are all still present on your system. Openbox.org .debs and/or source installs don't include them in your root menu -- that's done by Debian developer magic. You can do it with a few simple steps in these instructions.